Polymeric acrylonitrile dissolved in an n, n-dimethyl carbamate ester of a polyhydric alcohol



United States Patent POLYMERIC ACRYLONITRILE DISSOLVED IN ANN,N-DIMETHYL CARBAMATE ESTER OF A POLYHYDRIC ALCOHOL Gaetano F. DAlelio,Pittsburgh, Pa., assignor to Koppers Company, Inc., a corporation ofDelaware No Drawing. Application'May 28,1951

SerialNo. 228,783

14 Claims. (Cl. 260--31.6)

This invention relates .to the preparation of compositions of polymericmaterials, and-to the productionof shaped articles therefrom. Morespecifically, the invention provides new and useful compositions ofacrylonitrile polymers, and shaped articles therefrom. Moreover, itprovides a method for preparing such shaped articles. The term polymersis intended herein; to include copolymers.

Very useful polymers have been prepared from'acrylonitrile with orwithout other polymerizable substances, for example, vinyl, vinylideneand other mono-ethylen-ic compounds, and conjugated diene compounds suchas butadiene, etc. These acrylonitrile. polymers possess desirablephysical and chemicalproperties including toughness and solventresistance to commonorganic solvents such as methyl and ethyl alcohol,acetone, ethyl: ether, ethyl acetate, hydrocarbon solvents, chlorinatedhydro: carbons and the like. Because ofthese properties, it has beenconsidered desirable that these polymeric materials be fashnoned intofibers, films and other shaped articles.

In accordance withthe present invention,- it has been found that newcompositions useful for the production of shaped articles such as, forexample, filaments, films and the like can be prepared by treatingacrylonitrile polymers with an N,N,-dirnethyl-carbamate ester of apolyhydric alcohol wherein the ratio of the number-ofN,N-dimethyl-carbarnate ester groups tothe number of carbon atoms in thealcohol group is between 1:1 and 1:15. By employing the methods of thisinvention, new fibers films and the like havingparticularly desirableproperties may be readily produced.

It has been known that. certain copolymers CQIlIfiiD: ing less than 85percent acrylonitrileare'soluble in nitroalkanes, such as nitromethane.This is true-when, the comonomer has substituent groupsv oflow..secondary valence bonding forces, such as acrylates, etc. However,if the comonomer or comonomers have substituent groups of highsecondary-valence bonding forces, then .the solvent resistance of theacrylonitrile copolymers. approaches or is equivalent to that ofpolyacrylonitrile, Examples of monomers which have highsecondary-valence bond.-. ing forces and which form acrylonitrilecopolymers of high solvent resistance are methacrylonitrile,fumaronitrile, vinylidene chloride, beta-cyano-acrylamide,methylbeta-cyano-acrylate and itaconamide. Copolymers. of these withacrylonitrile have strong solvent resistance re-. gardless of theproportions of these comonomers. used, permitting the use of muchlessthan 85 percent acryloni trile without loss of solvent resistance...This isillustrated hereinafter by Examples II through V which show thatacrylonitrile copolymers of 20-30.. percent vinylidene chloride areinsoluble in nitromethane and various,

other solvents but are soluble in the above-described, car: bamates.

It has been proposed to use concentratedaqueous solu-- tions ofinorganic salts. such as lithiumbromide, zinc chloride, sodium chlorideand sodiumsulfocyanide (Rein, U. S. Patent No. 2,140,921), .or' moltenquaternary ammonium salts such as benzyl.pyridiniumchloridetRein,v

U. S. Patent No. 2,117,210), in the preparation of compositions ofacrylonitrile polymers. However, these com: positions have been foundgenerally unsatisfactory, for. use in the formation of yarns and'films.The former-type of solution, upon extrusion into coagulating baths,gives shaped articlesthat contain largeamounts. of the inorganic saltsof the proposed solvent. The presenceof. the. foreign materials in theresultant compositions produce discontinuities which cause. weakness andbrittleness in the shaped articles. The compositions containing thequaternary ammonium salts are dark colored, indicating somedecomposition or reaction of the polyacrylonitrile in the presenceof themolten: salt, and the films or filaments obtained from such solutionsare generally extremely brittle, highly-colored and very weak.

It has also been proposed (Latham, U. S. Patent 2,404,714) that certaincompounds containing the dimethyl carbamyl group-may be used as solventsfor acrylonitrile polymers containing at least about percent byweightacrylo'nitrile only if the carbon content ofthe compound be withincertain-limits. These limits are set by the formula ll 0.. .--C---N CH!wherein m and n represent integers,. m being equal tot-or greater than1, and n being of such a value that the ratio n/m is equal to or lessthan 1.5, except that when m equals 1, It must equal-zero.

It has nowbeen found. thatthe new compositions of this invention may beproduced by dissolving jacrylonitrile polymers ini Ethylene bis NgNdimethyl-carbamate) ((CH3)2NCOOCH2)2 Propylenebis(N,N-dimethyl-carbamate) (CH3)2NCOOCH(CH3)CH2OOCN(CH3)2' Glyceryltris (MN-dimethyl-carbamate) (QHahNCOOCH:

(CHslzNOOO H (CH3)2NCO 0 H2. Glyceryl bis(N,Nedimethyl-carbamate) ,j

(CHtlaNC O 0.011:

HOH

onnmcoo on.

(CHQINCOO CH:

Diglyceryl tetra (N,N-dimethyl-carbamate),

(CHahNCOOOHa. CHrOO CN(CH':): ormm c o 0 on 0110 o omen):

CHr-O-CHi; Pentaerythrityl tetra('N,N-dimethyl-carbamate),

((CHa )zNCOOCHz) 4C Pentaerythrityl tris(N,N dimethyl carbamate),

((CH3)2NCOOCH2) sCCHzOH; etc.

These N,N dimethyl-carbarnates have been found very satisfactoryfor-dissolving polyacrylonitrile, acrylonitrile copolymerscontaining atleast 85 percent acrylonitrile, and acrylonitrile copolymerscontainingvarious proportions of the monomers'listed above-as having high'secondary-valence bonding forces, 'as well as-for any-acryloirliitrilecopolymers having less than 85 percent-acrylonitr c.

It has also been found that carbamates of polyhydric alcohols in whichthe ratio of N,N-dimethyl-carbamate ester groups to carbonatoms inthealcohol group is less than 1:1 or greater than 1:15 have varyingdegrees of solvent powers depending on the particular ratio. Some ofthese latter compounds can be used quite satisfactorily foracrylonitrile copolymers having considerably lower solvent resistancethan polyacrylonitrile. Moreover, these-relatively-poor solvents canoften be used as plasticiers or softeners for acrylonitrile polymers andcopolymers.

Withv the carbamate solvents. ofthis invention, there canbe usedauxiliary solvents suchas N,N-dimethyl foramide, N,N-.dimethylacetamide,.etc., and in certain cases,

with acrylonitrile polymers of lower solvent resistance,

the auxiliary solvents can be N,N-dieth-yl foramide, N,N--

diethyl acetamide, N,N-dipropyl foramide, nitromethane, nitroethane,etc.

I This invention will be more fully described by the following examplesalthough it is understood that the invention is not intended to belimited by these examples. These examples illustrate the use of theseN,N-dimethylcarbamates in preparing compositions of acrylonitrilepolymers. In these examples parts and percent are intended to mean partsand percent by weight.

Example I Example II A copolymer of 80 parts acrylonitrile and 20 partsvinylidene chloride is substantially insoluble in methyl alcohol, ethyl.alcohol, acetone, methyl acetate, butyl acetate, benzene, cyclohexane,dioxan, monochlorobenzene, and cyclohexanone. Likewise it is alsoinsoluble in ordinarily affective solvents such as nitromethane andnitroethane. A 10 percent solution of the same copolymer in glyceryltris(N,N-dimethyl-carbamate) is effected by stirring at roomtemperature. More concentrated solutions, for example, up to 20-25percent or higher, are prepared by heating the mixtures to temperaturesup to and including the boiling point of the carbamate. In some casesthe solution is advantageously prepared under superatmosphericpressures. Fibers made from these copolymer compositions, heat-treatedunder tension for 1 hour at 150 C. and tested in boiling water show ashrinkage of about 3 percentmaximum.

Example III A copolymer of 60.parts of.acrylonitrile and 40 parts ofvinylidene chloride behaves in the same manner as the 80-20 copolymer ofExample II with regard to insolubility in the common organic solventsand in other highly polar solvents. However, solutions of this copolymerin propylene bis(N,N-dimethyl-carbamate) are readily prepared. Fibersfrom these compositions when heat-treated as in Example IL'show amaximum shrinkage of 2 percent. Tenacities of these fibers are in therange of 4-6 grams per denier, and elongations in the range of 12-20percent, depending on the methods and conditions of treatment. The wetstrengths of these fibers are practically equal to their dry strengths,

Example IV Aerylonitrile 835 332 I Parts Parts 9O 20 80 30 70 Example Vare substantially insoluble in methyl alcohol, ethyl alcohol, acetone,methyl acetate, butyl acetate, benzene, cyclohexane, dioxan,monochlorobenzeneand cyclohexanone.

Likewise they are insoluble in ordinarily effective solvents such asnitromethane and nitroethane. Solutions of these copolymers in ethylenebis(N,N-dimethyl-earbamate) and in glyceryl bis(N,N-dimethyl-carbamate)are readily prepared. These compositions can be used in the preparationof fibers having good tenacity and good heat resistance.

Example VI Copolymers of 95-90 parts of acrylonitrile and 5-10 parts ofvinyl chloride may be dissolved in ethylene bis-(N,N-dimethyl-carbamate) and in glyceryl tris(N,N- dimethyl-carbamate).Fibers from these compositions,

' when heat-treated under tension for one hour at 150 C.

r and conditions of treatment.

and when tested in boiling ,water, show a maximum shrinkage of about 3percent. Tenacities of these fibers are in the range of 4-6 grams perdenier and elongations in the range of 12-20 percent, depending on themethods The wet strengths of these fibers are practically equal to theirdry strengths.

Example VII Example VIII A copolymer of parts of acrylonitrile and 15parts of dimethyl itaconate is insoluble in nitromethane but is solublein ethylene bis(N,N-dimethyl-carbamate) and in glycerylbis(N,N-dimethyl-carbamate).

Example IX A copolymer of 95 parts acrylonitrile and 5 parts acrylicacid ShOWSzthC same solubility characteristics as indicated for thecopolymers of Examples II and III. Compositions satisfactory for thepreparation of fibers, films, foils, bristles, etc., are readilyprepared by dissolving this copolymer in ethylenebis(N,N-dimethylcarbamate) and in propylene bis(N,N-dimethyl-carhamate);

Example X Ten parts ethylene bis(N,N-dimethyl-carbamate) and partspolyacrylonitrile are ball milled for suflicient time to produce ahomogeneous mixture.

(a) This composition is moldable per se to produce uniform densearticles by standard molding processes using heat and pressure.

(b) Solutions of acrylonitrile polymers and copolymers are more readilyprepared by dispersing such a premilled mixture of the polymer inadditional ethylene bis- (N,N-dimethyl-carbamate) than with similarpolymers not so treated. The use of pretreated polymers permits theready dispersion of the polymers in the solvent and shortens the'timerequired for its solution.

The composition described in paragraph (a) of Example X, or similarcompositions made using the other carbamates described herein, may bemolded into cohesible structures, that is, it may be made cohesive underheat, under pressure, or under heat and pressure.

The N,N-dimethyl-carbamate esters described herein may be prepared fromN,N-dimethyl-carbamyl chloride by reaction, in the presence of anhydrogen halide acceptor such as pyridine or other bases especiallytertiary bases, with the proper molecular proportion of polyhydricalcohol to give the carbamate desired. For example, withN,N-dimethyl-carbamyl chloride, ethylene glycol in a molecular ratio oftwo to one respectively gives ethylene bis(N,N-dimethyl-carbamate),boiling point 167 0.; two molecular weights of N,N-dimethylcarbamylchloride with one molecular weight of propylene glycol gives propylenebis(N,N-dimethyl-carbamate); two molecular weights ofN,N-dimethyl-carbamyl chloride and one molecular weight of glycerinegives glyceryl bis- (N,N-dimethyl-earbamate); three molecular weights ofN,N-dimethyl-carbamyl chloride and one molecular weight of glycerinegives glyceryl tris(N,N-dimethylcarbamate); four molecular weights ofN,N-dimethyl- 5 carbamyl-chloride and one molecular weight of diglys ringives g yce y r eua(N N= ime y :a r arn etc. N,N-dimethyl-carbamylchloride is commercially avai a l an c a b P ared :b zth reaq n {ofphosgene with. dimethyl amine.-

The N me y a bama .d se i e herei hav beenfound-tobe good solventsandabsorbentsfor gaseous acidic anhydrides such as sulfur dioxide,carbonic acid anhydride, etc. Apparently the high secondary-v lencebonding forces which are believed to make these ,compounds such goodsolvents for acrylonitrile polymers also m k t em effeetive forretaining th se us anhydrides in solution. Moreover, when these solventshave sulfur dioxide, carbon dioxide, etc, dissolved therein, the solventpower toward the acrylonitrile polymers is reduced. This fact may beused to advantage in certain instances to reduce the swelling andlumping effects of thesolvents on acrylonitrile polymer particles..Usually when theacrylonitrile polymers are added to these solvents, thesolvents swell and soften the polymer particles and promote a tendencyfor the particles to agglomerate and lump. This lumping makes stirringdifiicult and delays solution. However, the practice of decreasing thesolvent power of the solvents of this invention by the use of gaseousacidic anhydrides, preferably those inert to the components andconditions of the solution, such as sulfur dioxide and carbon dioxide,

has been found to facilitate mixing and stirring since the lumpingtendency of the polymer particles is thereby reduced. ,Then, as thetemperature of the solvent is raised, the gaseous anhydride is graduallydriven off thereby restoring the solvent power and permitting thesolvent ,to dissolve the polymer.

Fibers having especially advantageous properties, such as highorientation, high tenacity, high elastic recovery and low shrinkage, canbe prepared from compositions of this invention by using acrylonitrilecopolymers of vinyl and vinylidene chloride. These copolymers aredescribed as copolymers of acrylonitrile and at least one other compoundhaving the formula wherein X is hydrogen or chlorine. In thesecopolymers, as well as in the other acrylonitrile copolymers, theacrylonitrile content in the polymer molecule is preferably at least 50per cent, although in some cases copolymers having not less than 80percent acrylonitrile are particularly advantageous.

For various purposes it may be desirable to chemically and physicallymodify the polymeric compositions of this invention by the presence ofother materials. The N,N- dimethyl-carbamates used in this invention arealso useful in the preparation of mixtures of acrylonitrile polymerswith various modifying agents such as other polymers, for example,polyvinyl chloride and polyvinylidene chloride, partial solvents ornon-solvents, or mixtures of these, pigments, dyes, plasticizers,stabilizers, spinning agents, incrustation inhibitors, etc.

Typical of the copolymerizing monomers which may be used withacrylonitrile in addition to or in substitution for those alreadymentioned are: acrylic acids, esters and amides, including theiralpha-methyl and alpha-chloro derivatives; maleic and fumaric acids,esters and amides; itaconic acid and esters; vinyl aryls, such asstyrene, vinyl naphthalene, vinyl diphenyl, vinyl fluorene, etc., andtheir alkyl, halogen, cyano and alkoxy substitution products, forexample, ortho-, meta-, and para-methylstyrenes, dimethyl-styrenes,ortho-, meta-, andparachloro-styrenes, dichloro-styrenes, ortho-,metaand paracyano-styrenes, dicyano-styrenes, ortho-, metaandparamethoxy-styrenes, monoand diethyl-styrenes, vinylmethyl-naphthalenes, vinyl chloro-naphthalenes, vinylcyano-naphthalenes, etc.; alpha-methyl-styrene, alpha,para-dimethyl-styrene, isopropenyl-naphthalenes, etc.; vinyl fluoride;tetrafluoroethylene; trifluorochloroethylene; isobutylene; ethylene;vinyl pyridines; vinyl esters; vinyl ethers; vinyl carbazole; N-vinylimides; etc.

The acrylonitrile polymers and copolymers may be prepared by anysuitable polymerization method, such as the ammoniumpersulfate-catalyzed polymerization of monomer or monomers dissolved oremulsified in water, or by a suspension process using organic peroxidecatalysts, etc. Molecular weights of these polymers and copolymers arepreferably within the range of 10,000 to 250,000 or even higher,although polymers having molecular weights i6 between 40,000 and 1150,000 may be; used :with particular advantage. However, polymersofmolecular weight less than 10,000 may .be used for othervpurposes,suchas impregnants, solvenhresistant coatings, etc. The Staudinger,equation permitsevaluation of molecular weights by. viscositymeasurements: 1

Molecular weight= f wherein K 1.5 X 10- for many acrylonitrile polymers;w Vi scosity of solution 1 Viscosity of solvent and C The concentrationof the polymer in the solvent gas-grassed in molarity per 1000' ml. ofsolvent at The molecular weight of the polymer or copolymer is dependenton the concentration of monomer or monomers, the amount and type ofcatalyst, temperature of reaction, etc.

As mentioned above, the compositions of this invention are especiallyuseful in the preparation of fibers, filaments, films, etc., either bydry spinning or by wet spinning into coagulating baths of water,glycerine, acetic acid, aqueous salt" solutions or other suitableliquids or mixtures of liquids which are miscible with theN,N-.dimethyl-carbamates described herein but are nonsolvents orprecipitants for the dissolved polymers.

Inma y eases, the rmed a t cl may be cold-drawn when substantially freefrom these N,N-dimethyl-carbamates. In other cases, a plasticizingeffect may be obtained when the polymer contains small quantities, thatis,

1-10 percent of one of these N,N-dimethyl-carbamates. In such lattercases, the carbamate acts as a plasticizer and the formed polymer can becold-drawn at a lower temperature than the corresponding acrylonitrilepolymer free of plasticizer. Acrylonitrile polymers plasticized with anN,N-dimethyl-carbamate in accordance with the practice of this inventionare particularly adapted to the preparation of molded articles orextruded forms such as rods, tubing, etc. Many of the formed articles ofthis invention may be cold-drawn up to 600-800 percent or more andthereafter heat-treated in the stretched form at temperatures of -185"C. but preferably at temperatures of -155 C.

Fibers obtained in accordance with the invention can be stretched tooriented structures of high tenacity and high elastic recovery. Thesestretched fibers exhibit characteristic X-ray patterns showingorientation along the fiber axis. Yarns made from these fibers can beused in making stockings and, because of their heat-resistance, can alsobe fashioned into more general, all-purpose fabrics such as for blouses,suits, skirts, awnings, or for towropes resistant to sea-water, etc. Thecompositions of this invention are also suitable for use in thepreparation of various other shaped articles and also for use aslacquers or coating compositions. Moreover, products obtained from thesecompositions are practically free of undesirable salts and especiallyimpervious to moisture and solvents.

The subject matter of this application was disclosed in applicationSerial Number 69,625, filed January 6, 1949,

and abandoned prior to the filing date of the present application.

What is claimed is:

1. A composition of matter comprisng polymeric acrylonitrile and an N,N-dimethyl-carbamate ester of a polyhydric alcohol wherein the ratio ofthe number of N,N- dirnethyl-carbamate ester groups to the number ofcarbon. atoms in the alcohol group is between 1:1 and 121.5.

2. A composition of matter comprising ethylene bis-(N,N-dimethyl-carbamate) and polymeric acrylonitrile.

3. A composition of matter comprising glyceryl tris--(N,N-dimethyl-carbamate) and polymeric acrylonitrile.

4. A composition of matter comprising propylene bis--(N,N-dimethyl-carbamate) and polymeric acrylonitrile.

5. A composition of matter comprising ethylene bis-(N,N-dimethyl-carbamate) and a polymer of acrylonitrile containing inthe polymer molecule at least 50 percent by weight of acrylonitrile.

6. A composition of matter comprising a polymer of" acrylonitriledissolved in ethylene bis(N,N-dimethylcarbamate) said polymer containingin the polymer molecule at least 80 percent by weight of acrylonitrile.

7. A composition of matter comprising an N,N-dimethyl-carbamate ester ofa polyhydric alcohol, wherein the ratio of the number ofN,N-dirnethyl-carbamate ester groups to the number of carbon atoms inthe alcohol group is between 1:1 and 1:1.5, and a copolymer ofacrylonitrile and at least one compound having the formula wherein X isa member of the class consisting of hydrogen and chlorine, saidcopolymer containing in the polymer molecule at least 50 percent byweight of acrylonitrile and said copolymer being dissolved in saidN,N-dimethylcarbamate.

8. A composition of matter comprising ethylene bis(N,N-dimethyl-carbamate) and a copolymer of acrylonitrile and vinylidenechloride, said copolymer containing in the copolymer molecule at least50 percent by weight of acrylonitrile.

9. A composition of matter comprising propylene bis-(N,N-dimethyl-carbamate) and a copolymer of acrylonitrile and vinylidenechloride, said copolymer containing in the copolymer molecule at least50 percent by weight of acrylonitrile.

10. A composition of matter comprising glyceryl tris-(N,N-dimethyl-carbamate) and a copolymer of acrylonitrile and vinylidenechloride, said copolymer containing in the copolymer molecule at least50 percent by weight of acrylonitrile.

11. A composition of matter of claim 2, in which the polymer has amolecular weight between 10,000 and 250,000.

12. A fiber comprising polymeric acrylonitrile and anN,N-dimethyl-carbamate ester of a polyhydric alcohol,- in which esterthe ratio of the number of N,N-dimethylcarbamate ester groups to thenumber of carbon atoms in the alcohol group is between 1:1 and 1:1.5.

13. A fiber comprising an N,N-dimethyl-carbarnate ester of a polyhydricalcohol, in which ester the ratio of the number ofN,N-dimethyl-carbamate ester groups to the number of carbon atoms in thealcohol group is between 1:1 and 1: 1.5, and a copolymer ofacrylonitrile and at least one compound having the formula ReferencesCited in the file of this patent UNITED STATES PATENTS Name Da Number teLatham July 23, 1946

1. A COMPOSITION OF MATTER COMPRISING POLYMERIC ACRYLONITRILE AND ANN,N-DIMETHYL-CARBAMATE ESTER OF A POLYHYDRIC ALCOHOL WHEREIN THE RATIOOF THE NUMBER OF N,NDIMETHYL-CARBAMATE ESTER GROUPS TO THE NUMBER OFCARBON ATOMS IN THE ALCOHOL GROUP IS BETWEEN 1:1 AND 1:1.5.